Why do the Mishnah and Beraisa need to repeat itself with regard to these
different types of coins? The Mishnah and Beraisa need only teach this in
one case, and then we would know that whenever there is an unspecified
amount of "coins" (in the plural) -- regardless of what type of coin -- the
creditor may collect only two! (TORAS CHAIM, TOSFOS YOM TOV; see SHINUY
NUSCHA'OS in the Mishnayos, and DIKDUKEI SOFRIM #7.)
(a) The PNEI SHLOMO answers that the Mishnah (and Beraisa) is teaching a
Chidush in each case. Since the subject of the Shtar is coins, which are
divisible entities, we might have thought that even though the word used is
plural, it refers not to two coins but to one and a half coins. The Mishnah
is teaching that the creditor is entitled to more than one and a half
coins -- he is entitled to take two full coins of the specified
denomination, because if it is true that the borrower only borrowed one and
a half coins (such as a Sela and half a Sela), then the value of the
half-coin would have been expressed in terms of a smaller denomination (a
Sela and two Dinarin).
The Pnei Shlomo adds that this is also why the Mishnah and Beraisa use the
phrase, "It is not less than two...," instead of saying, "He may only
collect two." "It is not less than two" excludes a *lesser* amount, and
implies that we might have thought that the creditor is only allowed to
collect an amount which is less than two (such as one and a half). "He may
only collect two" excludes a *greater* amount, and implies that we might
have thought that the creditor should collect more than two. Since the
Mishnah is teaching that he *may* collect more than just one and a half, it
says, "It is not less than two."
The Mishnah and Beraisa, therefore, needed to teach this Chidush with regard
to each denomination of coins, since we would not have been able to learn
one from the other. People might write "one and a half Zuzin" without
expressing the fractional Zuz in terms of a smaller denomination. Therefore,
the Mishnah must teach us in each case that the plural word is not less than
two.
(b) The TIFERES YISRAEL explains that each case in the Mishnah is necessary
for the following reasons. In the case of "Kesef Zuzin which are...," where
the number of Zuzin was erased, we might have thought that the creditor is
entitled to collect four Zuzin, since the words "Kesef Zuzin which are..."
imply that the author of the Shtar is defining an equal value for "Kesef
Zuzin." The lowest number of Zuzin which are equivalent to a different coin
is four, and the Shtar originally said, "Kesef Zuzin which are one Sela."
Therefore, the Mishnah needs to teach us that the creditor may only collect
two Zuzin, because perhaps the author of the Shtar was giving a number of
Zuzin, and not an equivalent value in another denomination.
In the case of "Kesef Sela'in which are...," where the number of Sela'in was
erased, we might have thought that the author of the Shtar was referring to
two *inferior* Sela'in (as mentioned earlier in the Mishnah), which are
equal to seven Zuzin (or 6 2/3 Zuzin), and not 8 Zuzin, and the Shtar
originally read, "Kesef Sela'in which are seven Zuzin." Therefore, the
Mishnah teaches that the creditor may collect two standard Sela'in and not
inferior ones.
In the case of "Kesef Darkonos which are...," where the number of Darkonos
was erased, we might have thought that certainly the author of the Shtar was
referring to inferior Darkonos, for the following reason. A Darkon is a
large, valuable gold coin, and people do not usually pay back debts with
such coins. Accordingly, we might have thought that the author of the Shtar
meant inferior gold Darkonos, and that is why he was writing the actual
value of the Darkonos, which was *less* than the value of two standard
Darkonos. Therefore, the Mishnah needs to teach us that the creditor is
indeed entitled to collect two normal Darkonos and not inferior ones.